Turbine plant



March 22, 1938. A. HANSCHKE TURBINE PLANT Filed Jan. 16, 1937 5 Sheets-Sheet 2 aw MM Hm TURBINE PLANT Filed Jan. 16, 1957 3 Sheets-Sheet 7 QM mm HM Patented Mar. 22, 1938 UNITED STATES PATENT OFFICE TURBINE PLANT Germany Application January 16, 1937, Serial No. 120,892 In Germany February 3, 1936 5 Claims.

The invention relates to turbine plants and has particular reference to marine turbine plants having several casings and comprising a doubleflow high pressure turbine the two parts of which comprise a different number of stages for the same drop of heat to be utilized by each part in parallel connection, and in which at low speeds the high pressure part having the greater number of stages is connected behind the other high pressure part in respect to steam supply. In a turbine plant of this type a number of stages of the twodouble flow parts, which would be suitable in steam-technical respects, cannot conveniently be lodged in one casing for constructional reasons. For,-a manifold subdivision of the high pressure drop may result in a comparatively great number of stages and thereby, particularly in the doubleflow arrangement, also a very great distance between the bearings of the shaft of the high pressure turbine. Consequently for reasons of strength and with regard to the critical rates the shaft must be made excessively thick; This entails the further result of large stufiing box losses. In addition, the utilization of the steam by the blades is unfavorable due to the latter becoming shorter with increasing wheel diameter. Finally, the pinions mounted on the individual turbine shafts and meshing with the gear transmitting the whole power to the propeller shaft are loaded too unequally, if the share of the whole drop worked up in the high pressure turbine exceeds a determined amount.

In order to avoid these drawbacks, according to the invention individual stages are withdrawn from the double-flow casing of the high pressure turbine and are lodged in another casing, while the relation to their high pressure part, in respect to steam connection, is maintained.

In order that the invention may be clearly understood and readily carried into efiect, two embodiments of the same are illustrated by way of example in the accompanying drawings, in which Figure 1 shows the high pressure part and intermediate pressure part of a multi-casing plant,

Figure 2 shows a. turbine plant comprising a high pressure turbine, an intermediate pressure and a low pressure turbine, these turbines being distributed in four casings, and

Figure 3 shows by the Mollier diagram (heat content-entropy) the utilization of the steam in the stages of the high pressure and intermediate pressure turbines according to Figure 1, the two parts of the double-flow high pressure turbine, which may be designed either for equal or unequal quantities of steam in parallel connection, being connected in series.

The first divison of the turbine plant according to Figure 1 consists of a double-flow high pressure turbine I, the other division of a single-flow intermediate pressure turbine, to which may be attached a low pressure turbine (not shown). The two shafts of the high pressure and intermediate pressure turbine act through a gear 4 upon a common propeller shaft 28. The live steam pipe 29 leads through 3 stop valve 5 to the nozzle chamber I of a Curtis stage 911. Behind this stage is the wheel chamber I! to which are attached three pressure stages 9b, 9c, 9d. In addition, a by-pass pipe 26 branches ofi from the wheel chamber II, which pipe comprises a valve 21 and opens into the chamber I8 of the other high pressure part I0. On this side of the casing are likewise provided three pressure stages IIlb, Illa, Ital. A fourth stage Inc belonging to the last-named high pressure part Ill is not lodged in the casing of the high pressure turbine I, but in the casing of the subsequent intermediate pressure turbine 2. Hence, separate ducts 30, 3i in the present case connect the outlet branches I I and I2 of the two high pressure parts with the casing of the intermediate pressure turbine. Only the by-pass pipe 30 coming from the outlet branch I2 of the stages I01 I00, IIld leads to the fourth stage Ille. The other by-pass pipe 3| coming from the outlet branch I l and provided with a stop valve 2I opens behind the stage We into the other casing of the turbine plant. Between the outlet branch II and the chamber I8 is provided a connecting pipe 22 comprising a stop valve 20.

The steam is led in such a manner, that at high speeds, that is, with parallel connection of the double-flow high pressure turbine I the whole quantity of live steam is led first through the Curtis stage 9a common to the two high pressure parts and then is divided. One partial quantity is utilized in the stages 91), 9c, 9d and thereupon led through the outlet branch I I to the intermediate turbine 2. The other partial quantity is supplied through the by-pass pipe 26 to the other high pressure part III. This latter quantity is led, after having passed through the stages Iilb, IIlc, Iild and through the outlet branch I2 and pipe 30, through the additional stage We arranged in the other casing, previous to its union with the other partial steam quantity. The stage we thus belongs to the high pressure part I 0, in respect to steam flow. Thereupon takes place the second utilization of the whole steam quantity in common in the stages 2a-2f. In some cases the steam leaving the outlet branch [5 of the intermediate turbine 2 is further led to a low pressure turbine (not shown) or is further utilized in any other way. With the parallel connection the stop valve 29 is closed and the valve 26 opened.

For the series connection of the two high pressure parts which is to be employed for low speeds, the adjustment of these two valves 29 and 2! is inverse. Now the whole steam quantity after having acted upon the Curtis stage 9a takes its way through the stages 9b, 9c, 9d. To this end the stop valve 21 of the by-pass pipe 25 must be closed. The steam then flows from the outlet branch ll through the pipe 22, which is now open, into the chamber l8 and thus is utilized further behind the part 9 in the stages of the other high pressure part [0. Thereupon the steam comes through the stage llle to the stages 20-21 of the intermediate turbine. The further utilization of the steam is the same as with the other connection.

In the second embodiment illustrated in Figure 2, in addition to the arrangements made in the first embodiment in accordance with the invention, also several stages of that part, 9, of the double-flow high pressure turbine, which at low speeds is connected in front of the other part, in respect to steam supply, are withdrawn from the double-flow casing. These stages are lodged in a special casing 32, while their relation to their high pressure part 9, in respect to steam supply, is maintained. In this case the whole plant, which consists of a double-flow high pressure turbine l, a single-flow intermediate pressure turbine 2 and a singleor double-flow low pressure turbine 3, thus comprises four casings. The stages of every casing act through a pinion upon the great gear wheel 4 mounted on the propeller shaft 28.

In this arrangement the steam is supplied in the following manner: Firstly, the whole steam quantity acts upon the Curtis wheel 9a, whereupon, with the high pressure turbine in parallel connection, the stages 9b9g and the stages l0bl0h are traversed by two different portions of the steam moving in two parallel branches. The steam leaving the stage 99 is led to the easing of the intermediate pressure turbine 2 in front of the first intermediate pressure stage 2a and there unites again with the other steam which has passed through the stages lllb-lllh. The stages of the low pressure turbine 3 are traversed in common behind the intermediate pressure turbine likewise by the whole steam quantity; the low pressure turbine may, however, be constructed in known manner as a double-flow turbine.

With series connection of the two parts of the high pressure turbine the steam quantity is not divided behind the Curtis wheel, but is led in closed current through the stages 912-99 and thereafter through the stages |0b-l0h. Thereupon the steam acts upon the stages of the intermediate pressure turbine and low pressure turbine in the same manner as with parallel connection. The courses of the steam for parallel connection on main run and for series connection on cruising run are plotted in the drawings by dot-and-dash arrows and by dotted arrows, respectively.

A special characteristic of the invention resides in the distribution of the steam between the two double-flow parts 9 and IU of the high pressure turbine. Ifthe stages of the parts 9 and II] are so determined that equal steam quantities pass through them with parallel connection, then with series connection the stages of the part l0 which is traversed second converts a greater drop in every stage than the pressure stages of the other part 9, due to the greater specific steam volume compared with the state of the live steam. Consequently also the exhaust losses of the last stage of the part In become very great and the efiiciency of the turbine is unfavorably influenced in a corresponding manner. Therefore, in order to obtain the most uniform stage drop in the two high pressure parts 9 and II], with series connection, the stages of the part I0, which at low speeds are supplied last, are designed for a correspondingly greater steam quantity with parallel connection than the stages of the other part 9. These conditions are illustrated in Figure 3 by a Mollier diagram for the arrangement of the stages of a turbine plant according to Figure 1, in which diagram the dotted lines show the change of the state of steam in the series-connected stages of the two high pressure parts 9 and In, with uniform distribution of the steam to these parts, during parallel connection, and the full lines show the same with non-uniform distribution of the steam according to the invention. In the latter case 9 denotes the gain of utilized total drop obtained in the whole turbine plant.

The number of the stages which belong to the high pressure parts 9 and ill, in respect to steam supply, but are withdrawn from the double-flow casing of the high pressure turbine and are lodged in another casing is determined in each case so that the most uniform possible power is transmitted by the individual pinions to the great gear wheel.

What I claim and desire to secure by Letters Patent is:

1. In a turbine plant, a double flow high pressure turbine having blades forming an unequal number of stages in its two parts, means for supplying fresh steam to said two parts in parallel, means for cutting off the fresh steam supply from the part having the larger number of stages, a conduit for conveying exhaust steam from the part having the smaller number of stages to the inlet end of said other part, means for closing said last conduit, whereby the parts of said turbine can be connected in parallel, or in series, with the part having the larger number of stages last in respect to steam supply, in the series connection; one or more stages of said turbine being disposed in a casing separate from the other stages, and conduit means connecting said casings so as to maintain the supply of steam to all stages of said turbine in the same sequence as though they were in one casing.

2. In a turbine plant, a high pressure turbine and a lower pressure turbine, said high pressure turbine being in the form of a double flow turbine with blades forming an unequal number of stages in its two parts, means for supplying fresh steam to said two parts in parallel, means for cutting off the fresh steam supply from the part having the larger number of stages, a conduit for conveying exhaust steam from the part having the smaller number of stages to the inlet end of said other part, means for closing said last conduit, whereby the parts of said high pressure turbine can be connected in parallel, or in series, with the part having the larger number of stages last, in respect to steam supply in the series connection; a casing for each of said turbines, one or more of the stages of the part of the high pressure turbine having the larger number of stages being disposed in the casing of the lower pressure turbine, conduit means connecting the exhaust end of the part of said high pressure turbine having the smaller number of stages to the casing of said lower pressure turbine behind the high pressure stages therein, and means for closing said last conduit means.

3. In a turbine plant, a high pressure turbine and a lower pressure turbine, said high pressure turbine being in the form of a double flow turbine with blades forming an unequal number of stages in its two parts, a portion of said high pressure turbine being contained in a double flow casing, while some of the stages of the part of said high pressure turbine having the smaller number of stages are removed to a special casing, said lower pressure turbine being arranged in a third casing, means for supplying fresh steam to the two parts of said high pressure turbine in parallel, means for cutting off the fresh steam supply from the part having the larger number of stages, a conduit for conveying exhaust steam from said special casing to the inlet end of the part of said high pressure turbine having the larger number of stages, means for closing said last conduit, whereby the parts of said high pressure turbine can be connected in parallel, or in series, with the part having larger number of stages last, in respect to steam supply in the series connection; -means for conveying exhaust steam from said special casing to said third casing, shut-off means for said last means, and means for delivering the exhaust steam from the part of said turbine having the larger number of stages to said lower pressure turbine.

4.In a turbine plant, a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine, said high pressure turbine being in the form of a double flow turbine with blades forming an unequal number of stages in its two parts, a portion of said high pressure turbine being contained in a double flow casing, while some of the stages of the part of said high pressure turbine having the smaller number of stages are removed to a special casing, said intermediate and low pressure turbines being contained, re-

spectively, in two additional casings; means for supplying fresh steam to the two parts of said high pressure turbine in parallel, means for cutting off the fresh steam supply from the part having the larger number of stages, a conduit for conveying exhaust steam from said special casing to the inlet end of the part of said high pressure turbine having the larger number of stages, means for closing said last conduit, whereby the parts of said high pressure turbine can be connected in parallel, or in series, with the part having larger number of stages last, in respect to steam supply in the series connection; means for conveying exhaust steam from said special casing to said intermediate pressure turbine casing, shut-off means for said last means, means for delivering the exhaust steam from the part of said high pressure turbine having the larger number of stages to said intermediate pressure turbine, means for delivering the exhaust steam A from said intermediate pressure turbine to said low pressure turbine, a large gear, and four pinions meshing with said large gear driven respectively by the stages of said turbines in said four casings.

5. In a turbine plant, a double flow high pressure turbine having blades forming an unequal number of stages in its two parts, means for supplying fresh steam to said two parts in parallel,

means for cutting off the fresh steam supply from the part having the larger number of stages, a conduit for conveying exhaust steam from the part having the smaller number of stages to the inlet end of said other part, means for closing said last conduit, whereby the parts of said turbine can be connected in parallel, or in series, with the part having the larger number of stages last in respect to steam supply, in the series connection; the part of said turbine having the greater number of stages being designed for a quantity of steam which is larger than the quantity for which the other part of the turbine is designed by an amount such that in series connection all stages of both parts convert substantially the same heat drop.

ALBERT HANSCHKE. 

